The invention resides in an exhaust gas recirculation arrangement for an internal combustion engine with an air intake duct and an exhaust gas recirculation passage which extends into the air intake duct at a predetermined angle and which includes a passage section extending in the intake duct in the flow direction of the air in the intake duct.
In order to improve the combustion of internal combustion engines and to improve the exhaust gas quality, a part of the exhaust gases can be recirculated from the exhaust gas manifold to the air intake duct of the engine. It is important for an effective exhaust gas recirculation that the exhaust gas is uniformly mixed with the intake air and that the recirculated exhaust gas volume does not unintentionally change over the operating period or over the life of the engine, but that it is admixed to the intake air only dependent on the selected control parameters. Furthermore, the hot exhaust gases should not thermally overload the exhaust gas recirculation system.
EP 0 753 656 A1 discloses an exhaust gas recirculation arrangement including a pneumatic control device disposed on the air intake channel of an internal combustion engine and having a membrane with a rod, which extends through the air intake channel transversely to the flow direction through the channel and controls, by a valve member that is a valve disc connected to the membrane rod, the flow cross-section of the exhaust gas recirculation passage. The valve member which is highly heated by the exhaust gas and the membrane rod are cooled by the intake air flow. The impurities contained in the exhaust gas such as carbon and rust particles are said to be carried along by the exhaust gas flow without entering the space between the membrane rod guide structure and the membrane rod. In this way, locking of the valve is said to be prevented.
DE 30 01 413 C2 further discloses an exhaust gas recirculation arrangement including an exhaust gas recirculation pipe which is disposed between an exhaust gas pipe and an air intake passage. One end of the exhaust gas recirculation pipe which includes a receiver opening extends into the exhaust gas pipe and has a section which extends in the exhaust gas pipe coaxially therewith. The receiver opening extends in the exhaust gas pipe in the upstream direction, but is shielded regarding the exhaust gas flow by a pot-like cover.
The cover and a deflector for the exhaust gas to be recirculated keep small particles contained in the exhaust gas away from the exhaust gas recirculation structure. As a result, the amount of deposits in the gas passages of the exhaust gas recirculation system is reduced and the operability of the arrangement is improved. It is noted that solid particles in the recirculated exhaust gas increase the wear of the internal combustion engine, particularly of the pistons, the piston rings and the cylinders. In addition, they detrimentally affect the lubrication capabilities of the lubricating oil and consequently the bearings of the engine.
The circumferential wall of the cover may be so formed that, by a venturi effect, cross-section restriction or respectively, by a jet effect, small particles that may have entered are accelerated together with the gas flow but cannot follow a flow reversal of the exhaust gases by 180.degree. into the receiver opening because of their inertia. In this way, even fewer particles enter the exhaust gas recirculation arrangement.
In addition to the exhaust gas recirculation pipe, often a vent line for the crankcase enters the intake air duct generally ahead of a compressor. The vent gases include oil vapors and cause together with the particles contained in the exhaust gas undesirable deposits in the exhaust gas recirculation arrangement, which deposits detrimentally affect the operation of the control devices and which, over time, restrict the flow cross-section of the exhaust gas recirculation system.
DE 14 76 052 C1 discloses a vent arrangement for the crankcase of an internal combustion engine, wherein the vent pipe is connected to the venturi pipe of a carburetor at the smallest flow cross-section thereof. In this way, the vacuum in the vent line increases with increasing engine load.
It is the object of the present invention to provide an exhaust gas recirculation arrangement, which is improved especially with regard to the influence of the crankcase venting system.